Method and apparatus for a continuous production of plastic-foil articles in deep drawing



Nov. 7, 1961 F. BRUMMER 3, 1

METHOD AND APPARATUS FOR A CONTINUOUS PRODUCTION OF PLASTIC-FOILARTICLES IN DEEP DRAWING Filed Oct. 5; 1959 8 Sheets-Sheet 1 A Fig. 2.15 .1. 7 7

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METHOD AND APPARATUS FOR A CONTINUOUS PRODUCTION OF PLASTIC-FOIL.ARTICLES IN DEEP DRAWING Filed Oct. 5, 1959 8 Sheets-Sheet 2 Th rottLe,

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METHOD AND APPARATUS FOR A CONTINUOUS PRODUCTION OF PLASTIC-FOIL.ARTICLES IN DEEP DRAWING Filed Oct. 5, 1959 8 Sheets-Sheet 4 RectiferIndicator Lg luts FfiedrichBflimmcr Bfmm0%/M %/A%RNEYS Radiating SystemNov. 7, 1961 F. BRUMMER 3 0 METHOD AND APPARATUS FOR A CONTINUOUSPRODUCTION OF PLASTIC-FOIL ARTICLES IN DEEP DRAWING Filed Oct. 5. 1959 sSheets-Sheet 5 M watbcVaLve O p erat'ung C5 LL 1 Step by Ste Cross Barsuuichilg D istr Lbutor INVENTOR FrfwdrichBn'immcr W %NEYS Nov. 7, 1961F. BRUMMER 3,007,201

METHOD AND APPARATUS FOR A CONTINUOUS PRODUCTION OF PLASTIC-FOILARTICLES IN DEEP DRAWING Filed Oct. 5, 1959 a Sheets-Sheet a ME 3 E 207O 202 h a -.15. W L 2| Zl3 2n ZOI 204 INVENTOR. Ejedfuhfirzimmar BY z Z1ATTORNEYS NOV. 7, 61 F. BRUMMER 3,007,201

. METHOD AND APPARATUS FOR A CONTINUOUS PRODUCTION OF PLASTIC-FOILARTICLES IN DEEP DRAWING Filed Oct. 5, 1959 8 Sheets-Sheet 7 k 4 A\Y\\\\\\\\\\\\\\\\\\\\ \\\\\\\\A INVENTOR I Friedrylahfimmmzr 442$ & igToRNaYs Nov. 7,, 1961 F. BRUMMER METHOD AND APPARATUS FOR A CONTINUOUSPRODUCTION OF PLASTIC-FOIL ARTICLES IN DEEP DRAWING 8 Sheets-Sheet 8Filed Oct. 5, 1959 INVENTOR From cur /H Compressor F116 (Lrjch BriimmerATTORNEYS 3,007,201 Patented Nov. 7, 1961 tic METHOD AND APPARATUS FOR ACONTINUOUS PRODUCTIGN F PLASTIC-FOIL ARTICLES IN DEEP DRAWING FriedrichBriimmer, Dinkelsbnhl, Bavaria, Germany, assignor to Farbwerke HoechstAktiengesellschaft vormals Meister Lucius & Briining, Frankfurt am Main,Germany, a corporation of Germany Filed Oct. 5, 1959, Ser. No. 844,510Claims priority, application Germany Dec. 13, 1958 19 Claims. (CI. 1819)It is known to produce plastic containers, boxes, cups, dishes etc. andthe associate lids for the most varied purposes from a plastic foil bydeep drawing. To this end cold or heated foil sections by varying sizesare placed on the cavity of a drawing die and are drawn into the cavityof the die either hydraulically, by employing compressed or evacuatedair, or mechanically by means of a plunger matching the die cavity. 011termination of the drawing process the die is opened and the foilsection which now shows on its surface the hollow positive shapes of thedie cavities, is removed from it. The finished article is obtained inthat the cavity-moulded blanks are punched out of the foil section alongtheir outer demarcation line by means of a punching tool. This methodalways requires a drawing die and a punching machine and its output istherefore limited because cutting of the foil sections to be treated,heating and shaping of the blank and its transfer from the drawing dieto the punching machine require a comparatively large amount of time andcould hardly be autornatized without the employment of relativelyextensive apparatus.

The object of the present invention is a method of continuouslyproducing moulded articles from thermoplastic foils of syntheticmaterial by deep drawing which combines the operations of foil punchingand deep drawing. A further object of the invention is a deep drawingprocess which allows perfectly neat production of drawn articles and yetfurnishes an appreciably increased output. A further object of theinvention is a device for carrying the above method into practicalefi'ect.

According to the method of the invention, an endless foil web of athermoplastic resin, for example polyvinyl chloride hard foil, ispre-heated to softening point prior to entering the shaping tool, issubsequently marked by mechanical means along the periphery of the drawnarticle to be produced, and finally, at the same temperature, deep-drawnin a draw die either hydraulically or mechanically, or by employing bothoperational means either simultaneously or successively. Cooling andsetting of the marginal zones is effected by contact with the markingedges, while cooling and setting of the blank takes place in the toolcavity. The finished article is eventually severed from the foil webwithin the marking zone, embrittled during cooling, and ejected from thedie. Preferably advance and heating of the foil web is here controlledin dependence upon the degree of softening attained immediately prior toentering the zone of treatment. If at this time the plasticity requiredfor processing has already been attained, the advance mechanism isstarted which moves the particular zone of the foil web thus softenedinto the area of treatment. If plasticity is still too low, then theradiation intensity of the heating device is increased until plasticityhas reached the correct degree. In this way it is ensured that duringeach cycle of advancement a transverse area of the foil Web moved intothe processing zone has the same degree of plasticity previouslydetermined in accordance with the processed foil type and the type andsize of the draw die, and that the finished products will therefore beturned out in completely uniform quality.

If, as will be shown by the embodiment described below, heating of thefoil takes place at full force, it is possible to place by way ofprotection, particularly in case of irregularities of interruption ofthe machine cycle, a curtain of cold air in the shape of a luminarcurrent between heating elements and foil web, using a feeler exploringthe foil web. This current can be generated by compressed air and servesto maintain, by. means of the issuing volume of air which is regulatablein dependence on pressure, the foil temperature at the level requiredfor processing and to prevent burning or melting through of the foil webby overheating. In automatic operation the exploring feeler ispreferably coupled to the stepping mechanism which triggers thenext-following switching sequence and operational cycle.

Preferably the task of notching the foil web along the periphery of theblank to be processed is allotted to the drawing die which to thispurpose is suitably shaped at its upper edge and carries out the markingprocess during a separate first motion in co-operation with a suitablecounter edge. Any suitable device for carrying out the method accordingto the invention is to be characterized by the following essentialelements:

(A) A guide track for the foil web comprising a feed roller, guiderollers and preferably also a take-off roller;

(B) A mechanism for the discontinuous advance of the foil web over adistance corresponding to the overall height of the components (C), (D),(E);

(C) A heating device for the foil web, arranged along the guide track(A), preferably composed of separate heater elements displaceable inaccordance with the outline of the die in use;

(D) [A device for marking the foil web, arranged behind the heatingdevice (C) in foil running direction and comprising a notching ring anda counter edge;

(E) Drawing die plate and die closure plate with drawing and punchingtool interchangeably supported therein, arranged either behind themarking device (D) in foil running direction or preferably incorporatingthe latter, as described above;

(F) A pneumatic or mechanical, or a pneumatic-mechanical device for therelative displacement of drawing plate, die closure plate, marking ringand counter edge;

(G) A drive system com-prising a motor, oil pumps pressure reservoirsand pressure cylinders for all driven or displaceable parts; itnecessary, dual-stage pump for high and low pressure;

(H) An electric relay circuit with magnetic air-oil valves for theautomatic actuation of the movable parts in the operational cyclegoverned by the foil type and the draw die.

Useful additional developments are constituted by the auxiliary elementslisted below:

(I) A feeler exploring the plasticity of the foil web in the heatingregion, including a temperature control device or a protective shieldagainst burning;

(J) A braking device for the foil web;

'(K) A device eiiecting fine feed control for the foil web as well asshock attenuation;

(L) A stepping mechanism using eight or more time delay relaysadjustable individually in their delay times, and also an associate plugswitchboard for varying the progress-ion of the operational cycle,pre-determined by the time delay relays, in accordance with therequirements of the draw die in use and the type of material beingprocessed.

In the attached drawings an exemplary embodiment of a device accordingto the invention is illustrated.

The method of the invention and the device intended for the realizationof this method, in contradistinction from previous non-cutting shapingmethods, aim at a sequence of the operational stages which form thedrawn product comprising accurately stepped individual stages.

In deep drawing within the range of elastic elongation of the foilmaterial, the operational stages following upon one another are listedbelow:

(1) Heating to within the temperature range of elastic elongation,

(2) Foil advance,

(3) Marking,

(4) Drawing or stretching,

(5) Pressing the drawn material to cold wall portions to achievesetting,

(6) Opening of the die,

(7) 'Detaching the blank,

( 8) Eject-ing the blank.

In drawing within the temperature range of plastic flow (a definition ofthis range is given in the Belgian Patents 597,545 and 550,620), whichfrom certain points of view offers special advantages, the followingoperational stages take place:

(1) Heating to within the temperature range of elastic elongation,

(2) Advance and redirection of the foil web into a horizontal plane,

(3) Heating to within the temperature range of plastic flow,

(4) Marking,

(5) Drawing or stretching,

(6) Opening the die,

(7) Detachment and simultaneous ejection of the blank.

FIG. 1 shows a device in vertical section, without the draw die, dieclosure plate and notching device being fitted. FIG. 2 shows a sectionin the plane CD of H6. 1, FIG. 3, a. section in plane GH, FIG. 4, asection in the plane EF wherein the draw die, die closure plate andnotching device are fitted. FIG. 5 shows, in a horizontal section, theinterconnected movable and rigid parts of FIG. 4. FIG. 6 showsdiagrammatically the action of the brake for the foil web (a) and theweb path without such a brake (b). FIG. 7 shows details of the fine feedregulation, FIG. 8 details of the throttle device 61 of FIG. 1. FIGS. 9and 9A represent the entire switching layout of the electric section ofthe machine. FIG. 10 shows details thereof. FIG. 11 is a diagram forcarrying out the shaping of the foil web in the plastic flow range.

FIG. 12 is a diagrammatic view of a film clamping and advancing devicein various phases of movement.

FIG. 13 shows a die with a plastic foil forming part of a punchingdevice not further illustrated.

FIG. 14 shows a die according to FIG. 13, but with a support elementinserted therein, said element being downwardly open, and with apressure ring imposed.

FIGS. 15-17 show a device according to the invention constructed in adifferent way in various operational stages.

FIGS. 18 and 19 are cross-sectional views in elevation of otherembodiments of this invention in two phases of operation, and

FIGS. 20 and 21 are views in elevation, partially in cross section andpartially diagrammatic of pressure cylinders and associated devices formoving the die-carrying plates of embodiments of this invention.

Identical parts have identical reference symbols in all drawings.

The whole device is arranged in a structure constituted by an angle ironframe lower part 1, an angle iron frame upper part 2, a transverse beam3 with longitudinal bars 4 and their extensions 5 and guide rods 6. Theextension arms 5 serve for the deflection of the foil when shaping bydrawing is not effected within the temperature range of elasticelongation, but in the higher temperature range of plastic flow. Shapingin this range when using suitable foil material offers advantages inregard to drawing and static stability. But during this kind oftreatment the foil should extend horizontally and should be treated inthis position, i.e. in a vertically directed drawing operation.

The guide train (A) for the foil web 34 consists of the feed spindle 35and the roller 33 fitted thereto for receiving the foil web to beprocessed, deflecting rollers or deflecting surfaces 38, 72 and 72, 39as well as the take-off spindle and take-off roll 40 fitted theretowhich is driven by a motor 44 by means of a spindle-actuating drive withslipping clutch 43. In order to feed the leading end of the foil web onto the take-off reel 40, a trough 41 leading to the spindle is provided.The removal of the full take-off reel 40 and the insertion of a newempty reel are effected with the aid of a resilient spindle release 42constructed in known manner (FIG. 3). Preferably the feed spindle 35 isalso provided with a band brake 36 attached to the lever 37 one end ofwhich is pivotaoly supported whereas the other end carries thedeflection or conveying roller 38. The same applies to the previouslymentioned take-off spindle 40. This arrangement ensures that the foilweb running off the feed roll is correctly guided in a loop and that theadvance movement does not jerk the entire mass of the roll into rotationbut takes place gradually, taking into account the inertia of the roll.

The advance mechanism (B) for the foil web comprises the vertical guiderods 20--preferably constructed as tubes to provide a system forhydraulic communication between the cylinders 27 and 28 withoutadditional ducts-which by the nuts 21 are fastened to the cross beams18, I9, guide frames 29, 30, pressure frames 31, 32 and hydraulicallyactuated pressure cylinders 27, 28 and, finally, counter pressuresupports 27a and 28a. The reciprocating vertical displacement of thefoil advancing frame consisting of the above mentioned components iseffected by the hydraulically actuated feed cylinder 26. In FIG. 1 thefeed frame is shown in its lowest position and the hydraulic pressurecylinders 27, 28 hold the pressure frame 31, 32 against the counterpressure supports 27a and 28a and thus hold the foil web, situatedbetween the counter pressure supports 27a and 28a and the pressureframes 31, 32, firmly secured between the latter. In this position theframe and the foil web arrested by it remain stationary for the durationof a notching and drawing operation to be described later. When thedrawing operation is terminated and the blank ejected from the openeddraw die, the pressure cylinders 27 and 23 pull back the pressure frames31, 32 within the guide frame 29, 30 and release the hitherto arrestedfoil web. Subsequently, by actuation of the feed cylinder 26, the wholefeed frame assembly is vertically displaced in an upward direction byone complete processing distance. When it has reached its upperposition, the pressure cylinders 27, 28 become active again and move thepressure frames 31, 32 towards the counter pressure supports 27a and 28auntil the foil web situated therebetween is again arrested. Now, owingto the opposite movement of the feed cylinder 26, the downward movementof the frame is initiated which in this way pulls downwardly to theextent of one processing distance the foil web gripped and arrestedthereby, which means that the next-following foil region has beenbrought into the processing position. The entire assembly of pressureframes and feed frames may also be replaced by rollers. Instead ofpressure frames and counter supports, 2 rollers pressing on one anotherare provided which are rotationally advanced in accordance with thedesired feed stroke.

Under certain conditions it may be preferable to arrange the feedmechanism for the foil to be processed as a combination of a stationaryand a movable clamping device for the foil web.

FIG. 12:: shows diagrammatically a simple movable clamping device inengagement with a vertically extending section of the foil web 34,whereas at 62 and 68 parts of the drawing and punching tool areindicated. In this arrangement the tool has to be opened before themovable clamping device can move downwardly together with the foil webclamped therein. Following this downward movement, the tool is closedwhile the movable clamping device has to remain stationary in its lowerposition. Only when the tool is again opened after the drawingoperation, the clamping device can again be opened and moved upwardly.This clamping device, therefore, must necessarily have a long stationaryperiod in its lower end position and should therefore be arrangedoutside the irradiation area of the heating device (not shown) for thefoil web, in order to avoid that the clamping device when stationary inits lowest position for a prolonged period should screen off part of theheat rays directed on the foil and thus prevent them from reaching thefoil, with the eifect that the heated area of the foil web is not heatedand softened uniformly. However, the arrangement of the only availableclamping device outside the heating area of the foil web necessitates anundesirably large overall height of the machine.

It is preferable, therefore, that the feed mechanism for the foil webconsist of a combination of a stationary and a movable clamping devicewhich in their movements are so related to one another that at any timeeither one or the other engages the foil web and clamps it, as shown inFIG. 12b. At first it is the movable clamping device, indicated byshaded areas, which engages the foil web and moves downwardly togetherwith the latter to the extent of one feeding stroke, whereas the otherclamping device, rigidly attached to the machine is opened (left drawingof FIG. 1211). As soon as the movable clamping device has reached theextreme point of its downward movement, the stationary clamping devicecloses and henceforth also clamps the foil web. It is thus not necessaryto wait until the tool 6263 which during the downward movement of themovable clamping device was of course still open, closes again and thusclamps the foil. The clamping had already been effected by thestationary clamping device. Consequently, the movable clamping devicemay be returned upwardly to its uppermost position immediately after ithas reached the lowest position of its feeding path and even before thetool has closed and gripped the foil. In order to attain independent andeffective operation of the clamping device, this can be actuatedindependently of the switching cycle of the machine since the operationof foil advance remains always the same. Since in this way the movableclamping device effecting the foil advance always stops in its lowestposition only for short periods and immediately, even before the toolhas closed and gripped the foil, returns to its upper position, there isno objection to the movable clamping device moving across the areawithin which the heat rays of the heating device fall upon the foil. Asthe movable clamping device confronts any point of this area only for ashort period, the intensity and uniformity of action of the heat rays onthe foil web is substantially unimpaired.

This improved feed mechanism renders the machine suitable also forprocessing stretched foil webs and foils consisting of such syntheticmaterials which, as for instance polyolefine foils, tend to buckle andtwist during heating for the deep drawing process unless they are firmlyclamped.

The heating device (C) for the foil web consists of the mounting panel51 with mounting screws 50 and 50a and the heat radiators 49, not shownin detail, for example constituting a bank of infrared radiators whosearea must substantially correspond to at least the maximum width of thefoil to be processed and to the maximum feed stroke, but shouldpreferably amount to a multiple of the maximum feed stroke.

If a single radiator is used the dimension of which corresponds exactlywith the width of the draw die and thus to a single feed stroke of thefoil web, and if the operational cycle covers for example 2 seconds,then a foilsection corresponding to one feed stroke must be broughtprecisely to the processing temperature within 2 seconds by a singleradiator. This necessitates a very high radiation intensity with a verysteep heating slope, and the smallest transgression of the cycle periodwill immediately lead to the burning of the foil, whereas even a smallshortening of the cycle period would result in the foil entering theoperational area of the draw die with a temperature rise falling shortof the predetermined processing temperature. On the other hand, if theheating area for the foil web is increased by the juxtaposition of fiveindividual heater elements to five times the extent of one feed strokeWhile the operating cycle is again fixed at 2 seconds, heating of thefoil to the desired identical processing temperature need not take placewithin one single operational cycle, but during a time corresponding tofive subsequent operational cycles, i.e. within 10 seconds, and theheating slope may be kept much flatter. In order to heat the foil bymeans of five successively arranged heating elements, for example from20 to 120 C., any single heater element only needs to impart to the foilsection confronting it at any time a temperature rise of 20 C. The firstradiator can here be so dimensioned that the foil in the compensatedcondition, i.e. when the irradiation is compensated by the heat losses,reaches a temperature of a little above 40 C. The second radiator issimilarly adjusted to a compensated condition of 60 C., the third to oneof C., the fourth to C. and the fifth to one of C. Consequently anyshortening or prolongation of the pre-determined cycle period of 2seconds can only lead to a fifth of a foil-endangering temperature riseor drop in the foil web, as compared with heating by a single radiator.The radiator bank radiates its heat to the foil area in oppositerelationship with it and raises this area to the pre-determinedprocessing temperature. Within the mounting slots the radiators 49 canbe individually elevated up to an angle of 30 C. This arrangement isparticularly advantageous for the working of round blanks in staggeredarrangement, but can also be used in the production of any other drawnarticles.

In the embodiment shown the notching device (D) and the draw die (E) arecombined with one another.

On the longitudinal bars 4 with their extensions 5 are arranged the feedguide plate 52 and the front plate 53. The front closure plate and theend plate 10 are rigidly connected to the guide rods 6. A reciprocatingmovement is imparted to them by the elbow lever 11 under the action ofthe hydraulic cylinder 12. Between the support plate 16 and the drawplate 14 are provided spacing rods 15. The displacement of the movableparts on the guide rods 6 is effected by the hydraulically actuated maincylinder 17. The hydraulic cylinder 12 is pivotably supported in point120. When the position is suitably vertical the piston rod is ejectedfrom the cylinder 1'2 during a simultaneous tilting movement of thewhole cylindereifected towards the right in this sectional view untilthe elbow joint is straightened. The tilting movement of cylinder 12taking place when the piston rod is extended and the elbow leverstraightened is indicated by the arrow in FIG. 1. In FIG.2, in the lowerpart of the section C-D, there appears the connecting shaft of the elbowlever assembly 73, indicated by a shaded area, which is provided with aU-shaped recess. This recess has been provided lest the cylinder whenextending, contact the main cylinder 17 prematurely. The parallellongitudinal elements appearing in FIG. 2 laterally of this U-shapedshaft are the lever elements 11, composed by larninations and arrangedto theleft and right thereof.

The elbow lever assembly is constructed in this way because, in it thepressure exerted in the straightened condition becomes infinite. But inmany cases it will be sufficient if the elbow lever assembly and thehydraulic cylinder provided for its actuation is replaced by adirectaction hydraulic cylinder.

The cylinder 26 is damped by a throttle 61 which is coupled to the levermovement of the throttle lever 23. The spring-loaded throttle levermoves upwardly when the feed mechanism is lifted. When the latter islowered, it will first abut on the throttle lever 23 which is therebysufficiently lowered to throttle the oil feed to the hydraulic cylinder26. In this way the impact of the abutting feed mechanism ishydraulically damped and the machine made noiseless.

FIG. 11 shows diagrammatically the redirection of the foil web fordrawing in the plastic flow temperature range. The foil web 34 arrivesvertically and is deflected by means of a roller or the like U into thehorizontal direction. An auxiliary movable radiator assembly S is movedout into a position below the horizontal portion of the web, in order toheat up this foil portion to the temperature of plastic flow. The tool Wnow works in vertical draw direction. When the blank is to be ejected,the movable radiator assembly S is preferably withdrawn. When thisoperational mode is chosen, the guide and pressure frames in the lowersection of the machine must be extended in accordance with the length ofthe extension arms.

The 90-angle E in the foil web is only being formed when the tool W isclosed. Prior to this, the foil web sags at this point, forming an are.This deflection of the foil web into a horizontal plane of treatment isnecessary to achieve universally identical wall thicknesses in the drawnarticles. If it were attempted to process foil heated to within thetemperature range of plastic flow in a vertically extending plane, i.e.in a horizontally directed drawing operation, then the blanks wouldreceive thicker walls in low situated regions during drawing, becausethe synthetic material in a state of plastic flow would already start toflow downwardly under its own weight even before the die could beclosed. On the other hand, for drawing within the temperature range ofelastic elongation processing of the foil in a vertical plane is moreadvantageous because then the heated foil web does not need any supportwhich would always lead either to the occurrence of cooled areas in thefoil or the foil material sticking to the heated support members. In thedevice according to the invention, however, supports are avoided inevery case, irrespective of whether the processing plane extendsvertically or horizontally.

The marking and drawing device (D), (E) consists of the drawing andnotching die 62 with vacuum duct 66, annular notching ring 63. andmovable clamping ring 65. This assembly is interchangeably mounted onthe draw plate 14. The punching plate 75 with its notching counter edge64 is mounted interchangeably to. the front plate 53. The die closureand notch limiting member 68 with its compressed air duct 69 and, ifnecessary, plunger 70 and the ball valve 71 for atmospheric compensationbehind the plunger is interchangeably mounted on the die closure plate7. Spacer bushes 8 and end caps 9 are provided on guide rods 6.

As is well known, it is impossible by punching to cut a syntheticarticle from a thermoplastic or similar foil since even the smallest gapin the tool components leads to inhaling of the plastic material. Here,the plunger draws a thin film through the gap between its cutting edgeand the die recess without severing the blank from the foil or likesubstance. In order to avoid this disadvantage, it is possible to letthe thermoplastic component to be punched out be pressed against asupport situated in a die recess, in order thereafter to let thepressure-loaded sandwich consisting of the thermoplastic component andthe support be driven through the die recess until the con- 8 nectionbetween the foil or like substance and the blank to be punched isruptured.

The advantage of this method rests in the fact that, when thethermoplastic blank is pressed against the support, the material of theblank is clamped in this region so that when a film is formed this isnot supplied with further material and will therefore be ruptured.

It is particularly advantageous if the outer marginal region of theplastic foil which surrounds the thermoplastic blank to be punched out,is covered by a pressure ring so that during punching continued filmformation between the plunger surface and the inner surface of the dierecess is prevented also in regard to this area. After a very shortperiod of film formation, the thermoplastic blank to be punched out issevered from the plastic foil.

In order further to reduce film formation between the thermoplasticblank to be punched out and the plastic foil, it is advisable that thethermoplastic blank should be pressed against a support fitting into thedie recess. If this is done, especially in conjunction with the stepdescribed in the previous paragraph, only a very small amount of plasticmaterial will be available for the formation of a film.

In order that the plunger and the thermoplastic component should beguided during the initial stage of punching it is preferable that theplunger in its co-operation with the die should at first travel acertain distance without pressing the thermoplastic component on asupport; only then is the thermoplastic component pressed against thesupport and the pressure-loaded sandwich is driven through the dierecess. Owing to the fact that there is no appreciable counter pressureduring the first stage of plunger movement, the plunger is introduced inthe (lie recess without the possibility of tilting. If counter pressureis encountered afterwards, the plunger will be incapable of evasivemovement, owing to being guided in the die recess.

Taking into account these considerations, it is of particular advantagein the method according to the invention it punching and shaping of thethermoplastic blank is effected in one and the same operation in such away that after pressing the thermoplastic component against a support, apull (suction) or pressure is exerted which sucks or presses, in ashaping action, the thermoplastic blank which is heated to at leastplastic flow temperature, into a cavity provided, for example, in saidsupport.

To carry out this modification of the inventive method serves a devicecomprising a support preferably fitting into the die recess whichsupport, together with the thermoplastic blank to be severed by theplunger, can be driven through the die recess by means of the plunger.

'Further details become apparent from the examples illustrated in thedrawings.

There are shown:

In FIG. 13 a die with a plastic foil forming part of a punching devicenot further illustrated,

In FIG. 14 the die according to FIG. 13 but with a support elementinserted therein, said element being downwardly open, and with apressure ring imposed, and in FIGS. 15 to 17 a device according to theinvention constructed in a different way, in various operational stages.

As shown in FIG. 13, a die 201 has a recess 202. A thermoplastic foil203 is placed on the die 201.

Further during the course of the operation, a support element 205 isinserted from below, in the direction of arrow 204, its upper surface206 being situated somewhat below the surface of the die 201, see FIG.14. The support member 205 has a flange 207 bearing on the die 201 frombelow and determining the position of the surface 206 of the supportelement 205. The support 205 has a cavity 208 through which during theoperation air can be discharged if necessary so that when athermoplastic component is punched out of a heated foil 203, a containeris formed in the space 208. The margin of the foil 203 adjacent aplunger 210 is pressed on the die 2M from above by means of a ring 209.A plunger 210 is provided above the foil 203 and the ring 209.

The device operates in the same way as will be described below.

From FIGS. 15 to 17 the various operational stages of a differentlyconstructed device can be gathered.

The reference numeral 202 denotes the recess of the die 201, and 203denotes the foil.

A plunger 211 movable in the direction of arrow 212 has an air passage213 through which compressed air is led underneath the plunger 211. Thesupport 214 fitting exactly into the recess 282 of the die 201 has aspace 215 into which a suitably heated thermoplastic component 216 whichis to be separated can be pressed by means of compressed airre-circulated through the duct 213. In the lower wall portion enclosingthe recess 215 of the support 214 there may be provided small-diameterbores (not shown) to avoid the creation of an air cushion in the recess215. The support 214 is pressed upward in the direction of arrow 2% bymeans of spring or like action not illustrated.

The device operates as follows: A suitably heated foil is placed uponthe die 201, as apparent from FIG. 13, then the support 214 is pushedfrom below into the recess 262 up to a stop 214 and the plunger 211 ismade to act. When the plunger 211 has partially introduced in the diethe foil portion 216 which is to be punched out, the thermoplastic 216is pressed against the support 214 with suitable force, and apressure-loaded sandwich is thus formed. At the instant this sandwich isformed the plunger 211, therefore, is already guided in the die 20 1,see FIG. 15. The effect of the compressed air acting through the duct213 of the plunger 21.1 on the thermoplastic blank is shown in FIG. 16.The blank 216 has now been drawn into the shape of a container 217 andis applied to the Wall of space 215 in the support memher 214.

A later stage is shown in FIG. 17. The sandwich constituted by theplunger 211, the support 214 and the container 217 is now presseddownwardly by the plunger 211 and pushed through the opening 202 of thedie 2%1. Upon retraction of the Plunger 211 and removal of the support214 carrying the container 217, an empty support 214 is introduced frombelow in the opening 282 of the die 261 in the manner shown in FIG. 14.The foil 203 has meanwhile been advanced suiliciently far for a newthermoplastic blank to be punched out.

Instead of air, an additional plunger can be used to press thethermoplastic blank into the recess 215.

The recess 215 can also be provided in the plunger in which case theupper surface of the support must be flat.

The device for producing a container may also be constructed asindicated in FIGS. 18 and 19.

A device of this type has a stationary flat plate 22%? and a verticallyreciprocating plate 221 spaced a suitable distance from the plate 221).The plate 221 is connected by means of a linkage 222 with a device forlifting and lowering, not shown here. Below the movable plate 221 isprovided a rigidly arranged annular knife 223 whose annular cutting edgepoints towards the movable plate 221 and is capable of co-operating withthe latter. Above the movable plate 221 is provided a verticallyreciprocating shaping plunger 225 (whose downward movement is limited bythe stationary plate 2241) which is capable of passing through anaperture 221' of the plate 221.

This device operates as follows:

On the knife 224 is placed a suitably heated flat portion of syntheticmaterial 226 and the movable plate 221 is then lowered towards theannular cutting edge 224 in the direction of arrow 227, and pressedthereon, until an annular notch 229 is formed in the flat portion 226 ofthe synthetic material and a thermoplastic blank 228 is marked by thisannular notch 229 and held thereby by the pressure between the parts 221and 224. If the shaping plunger 225 is now lowered in the direction ofarrow 23%, from the position shown in the drawing to almost the positionshown in FIG. 19, a container 231 is drawn into shape from thethermoplastic blank 228 held there in by the notch 229. Shortly beforethe shaping plunger 223 meets the stationary plate 220, the lowering ofthe plunger 223 having to be effected with suitably timed velocity, thematerial adjacent the notch 229 has set sufficiently, owing to heatconduction in the plate 221 and in the annular knife 223, that on theshaping plunger 225 being moved further, the container 231 is severed ortorn from the marginal area 232 of the flat portion 226 of syntheticmaterial. Thereupon the shaping plunger 225 presses the bottom of thecontainer 231 on the stationary plate 226) whereby the bottom is pressedflat.

When the container 231 has been severed, the stressed portion ofmaterial forming the outer wall of the container 231 is urged in thedirection of arrows 233 in a radial direction towards the shapingplunger 225 and may thus apply itself to the latter, whereupon it willbe chilled. When the shaping plunger 225 is withdrawn into the initialposition of FIG. 18, the container 231 slips off and is removed.

In FIG. 19 a stage is shown shortly after the container 231 has beensevered from the fiat portion 226, the shaping plunger 225 havingpressed flat the bottom of the container in co-operation with the plate220.

In the case of containers which need not have a fiat bottom the plate220 may be ommitted. Also, the plate 220 may have any desired shape, forexample an annular ridge or the like while the lower plunger surface maybe provided with a matching counter shape. The plate 220 can be madeheight-adjustable, according to the desired height of the container. Inthe drawings the draw die has been shown, for claritys sake, as a singledie for a conical cup. It is also possible of course to insert in themachine multiple dies for blanks of the most varied shape. Above all,the machine also allows processing with dies of considerable depth whichmay amount to a multiple of the die diameter. It would also be possible,thanks to the ideal control adjustment possibilities, to draw with thismachine elongated and very narrow cylinders (drinking straws).

The mechanical-hydraulic system for the mutual displacement of thevarious plates on the guide rods 6 comprising the main cylinder 17, theelbow lever closing mechanism 11 and the hydraulic cylinder 12 hasalready been described. To this must still be added the common driveunit comprising a motor 55, oil pump 56, oil reservoir 54, pressurereservoir 57, suction pipe 59 and pressure pipe 60 as well as theoil-air valves 58. This unit serves all the hydraulic and pneumaticelements (devices for ejecting the shaped articles from the mould andfor cooling the heated foils).

Within the foil web track one or more cold air jets 48 may be provided,capable of issuing from a narrow slot orifice a curtain of cold airalong the foil web it the latter is threatened with overheating by aninterruption of the operational cycle or by excessive heat from theradiators.

The pressure cylinders for moving the die-carrying plates may be sodevised that, as shown diagrammatically in FIG. 20, the full oilpressure is effective on the pressure face A, whereas on thedifferential face B only a smaller volume of oil, reduced owing to thelarge diameter of the rods of the differential pistons, is needed forthe moving apart of the die components. In this way the output per unitof displacement of the oil pump needed for the intended number ofoperational cycles per minute for which the machine must be adjusted, iskept within tolerable limits. But this kind of arrangement of pressurecylinders necessitates a rather extended machine construction and themovement of the frontal die carrying plate, indicated by arrow, requiresthe additional 11 movement of the lateral bars which results in thenecessity of having to move larger masses.

But the mechanism for actuating the die carrying plates can be madesmaller, more easily accessible and movable in that pressure cylindersare replaced by draw cylinders.

FIG. 21 shows the die carrying plates movable towards one another in thedirections of arrows in an arrangement such that they are moved by thedraw cylinders C, C and D, D. The draw cylinders may be arrangeddiagonally on the stationary machine frame. The cylinders C, C and D, Dact directly upon the die carrying plates to which they are allocatedand draw them in the direction of the movement-indicating arrows. Thisresults in a more compact construction than in the case of anarrangement as shown in FIG. 20 and comprising pressure cylinders.Access to the die carrying plates is not hindered by constructionalcomponents and the fitting and exchange of draw and punch tools isconsiderably facilitated. The draw cylinders may be equipped withthinner and lighter piston rods. On the whole, the weight of the movedparts is considerably reduced.

The fact that in this construction the draw face of the cylinders isutilized to generate high pressure may at first glance appear as adisadvantage, but this can be fully compensated by an additional step.The draw cylinder which is equipped with a light small-diameter pistonrod needs a certain amount of oil for its movement, in accordance withits dimensioning and hydraulic relationships. The pressure face of thecylinder is constituted by the full piston surface which for the purposeof opening and moving apart the die components does not however requirethe application of the full volume. In order to avoid having to feed theoil by means of the pump, it is possible to stress the fully availablepiston surface with a constant air pressure. Then the oil situated inthe rear part of the cylinder need not be conducted through thegenerator or the pump, but it can continuously pulsate in bothdirections, driven by the draw end of the cylinder.

FIG. 21 shows on the pressure side of the cylinders C, C a closedconduit system H leading to an oil reservoir F to which a constant airpressure G is applied by means of an air tank, not shown. All pressureconduits may be interconnected and are not controlled. The air pressurenow capable of reduction and the oil pressure as constituted by thereservoir F acts with constant force upon the pressure side of thecylinders, stressed by the pistons. The draw side of the cylinders canin this case be controlled by three-way valves, as distinct fromfour-way valves. When the oil pressure on the draw side is increased by10 atmospheres of excess pressure, for example, then, with counterpressure being constant, the oil volume present on the pressure side ofthe cylinder is simply urged back into the reservoir F as soon as thedraw side is stressed by means of the associate electric valve. Here thecontrolled oil volume supplied by the pump only amounts to a little morethan half the oil volume which must be controlled in the case of apressure cylinder according to FIG. 20 (with a pressure of increase 10atmspheres of excess pressure).

Obviously, the machine according to the invention is not confined to therelative distribution in space of the individual elements which has beenshown in the embodiment described. It is not absolutely necessary thatthe draw plane and the heating plane extend perpendicularly.

In particular, it is also possible to arrange the draw plane and with itthe assembly constituted by die closing plate, front plate, die coveringplate etc. so as to extend horizontally in which case the longitudinalbars 4, and the guide rods 6 must be positioned vertically. The feedunit with its vertical guidance 20, pressure frames 31, 32 could herestill remain in a vertical position or also be arranged horizontally.

The heating plane for pre-heating the foil web could also be arrangedobliquely or horizontally. But the vertical arrangement shown in thedescribed embodiment has proved itself particularly suitable inpractical operation, for various reasons. The essential content of theinvention is not a certain relative arrangement in space of theindividual constructional components, but the combination andinteraction of the functions of certain components indicated as beingessential. The embodiments described here put into practical effect thiscombination of functions and have also been tested in practice asregards their distribution in space, without however this combination offunctions being dependent upon the distributions in space presentedhere.

The electric part (H) of the machine consists of magnetic air/ oilvalves 58 which actuate the various moving and movable elements of themachine. These electric valves are controlled electrically by relays.This is preferably done by means of a step-by-step switching mechanism(L) and with the aid of eight or more time deiay relays which areindividually adjustable in their delay time. Each current pulse proceedsto two cross bar distributors one of which passes on the pulses for theconnection of the relays and the other the pulses for the interruptorseffecting disconnection of the relays. To start the machine, anextraneous pulse to the step-by-step switching mechanism is needed.

The relays act upon the magnetic air/oil valves or electric valves 58which start up the various actuating and movable elements of the machine(excpt motor 55 which is supplied from the mains network).

The step-bystep switching mechanism is a time-dependent unit whichserves for sub-dividing a certain period of time, i.e. the progress ofone operational stage, into arbitrarily selectable partial periods.These partial periods are marked by a pulse which applies a voltage andat the same time serves as a disconnection pulse. These pulses arecontinued indefinitely since the last relay again triggers the firstone. These finely graduated and freely selectable time steps arefollowed by an element which arranges the sequence of events, namly thecross bar distributor. At this point the magnetic valves are coordinatedby means of associate relays so that the running off of the singleevents is put in order. When effecting this coordination, the switchingsequences prompted by the step-by-step switching mechanism may be sochosen in their partial periods that individual events may overlap inany desired manner. It is possible, for instance, to let the firstconnection pulse of the step-by-step switching mechanism switch on thefeed mechanism. The second connection pulse closes the die, the thirdmarks the foil. The simultaneously created disconnection pulses whichare transmitted by way of the other cross bar distributor, remainineffective and are not employed for any of the functions. The fourthswitching pulse is derived from the disconnection end and serves, forexample, to return the feed mechanism again to its original position, byway of the magnetic valve; it is also feasible, by means of thesimultaneously generated subsequent connection and disconnection pulses,to connect and disconnect in each case a plurality of elements andcontrol means. In this way an untold amount of variants results in asystem having 64 connection and 64 disconnection sockets on a plugpanel, for example approximately 2815 10 variants. This enables theoperational cycle of the machine to be set for the special requirementsof each newly inserted die and of each new foil type. The optimumsetting for each new die is at first ascertained empirically and enteredaccording to plug positions on a chart showing the lay-out of the plugpanel. Each draw die thus has its appropriate chart and when such a dieis again fixed in the machine all that is needed is to insert the plugsin the panel in accordance with the appropriate chart so as to ensureoptimum functioning of the machine with this die.

In FIG. 9 the electric section of the illustrated embodiment of themachine is shown with a panel of 8X8 switch sockets.

The device (I) for exploring the plasticity attained by the foil web inthe heating area consists of a feeler 27 which indicates plasticity bythe depth of its penetration into the foil web and acts through theparallelogram linkage 46 upon the magnetic valve for releasing thecompressed air curtain which protects the foil from overheating. Ifdesired the surface temperature of the foil can also be determined inanother way, for example by pressing into con-tact a semiconductordevice (electric resistance measurement), with the result that only thetemperature of the foil surface is read directly or, upon a certaintemperature being reached, the compressed air curtain is released or,upon a predetermined optimum processing temperature being reached, thestep-by-step switching mechanism is triggered. The combination of feelerand foil brake provided in the illustrated embodiment was chosen for itsconvenience. But these two elements may very well remain completelyseparate from one another.

If the danger of scratching the foil surface is to be completelyeliminated, braking of the foil may for example be effected by means oftwo rollers pressed against one another whose ability to rotate can bebraked.

The foilbrake 45 has the object to prevent the foil web which is curvedaround various radii, from curving outwardly when the pressure frame 31is opened and the feed mechanism travels upwardly. Its operation isillustrated diagrammatically in FIG. 6a. The foil brake 45 preferablyconsists of a pressure beam lined with foam rubber, the beam beingcapable of being pivoted upwardly about its pivoting point (on the left)which is necessary for the foil web to be introduced. The foil brake 45acts continuously and guarantees that the foil web travels past itsdeflection rollers in a tensioned condition. If the foil brake isomitted, the foil web assumes arcuate positions and the feed distancesbecome inaccurate (FIG. 6b). This is of particular disadvantage if foilwebs are processed with printed images at regular successive intervalsalready printed thereon which require accurate register.

The fine feed regulation (K) with shock absorption is shown in FIG. 7.It comprises a transverse beam 24 whose end position is controlled bythe two parts 23. The dotted space 25a is variable by means of a settingscrew 25c in accordance with the depth of penetration of the settingspindle 25, by using a regulator wheel. The two regulator pins 25b thusemerge to a greater or lesser extent from the beam 24 or are furtherpushed in by the parts 23 upon contact with the feed mechanism. Coupledto the lever movement of the throttle lever 23 is the throttle 61. Thethrottle lever which is loaded by the spring 230 (FIG. 8) travelsupwardly when the feed mechanism is lifted. On being lowered the latterfirst contacts the throttle lever, presses it downwardly and thusthrottles the oil feed of the hydraulic cylinder, in order to elfectshock absorption. The feed regulation comprises a spacer 22 Whose lengthis matched with-the die in use and is interchanged along with thelatter. If in the regulation of foil webs bearing printed images thespacer 22 does not accurately coincide with the printing register thedescribed fine regulation is employed. It also allows, when the die isinstalled, to find and set the smallest possible distance betweenadjacent useful areas experimentally by reductions of this distance.

In the case of very thin-walled drawn articles the ejector provided hereis not satisfactory by itself because, owing to the plastic materialbeing charged with static electricity, the blanks may adhere to the diestoo firmly. For this reason there are preferably provided, in additionto the ejector which removes the drawn article from the die withoutdeformation, additional small pointed detaching members equipped with asmall spring. They ensure that the drawn article is mechanically urgedaway from the ejector which is usually shaped with a flat surface, andthus also from its electric field. In this way it can be achieved thateach drawn article drops out of the die fully automatically. In the caseof a draw piston the provision of a rubber ring seal is recommended lestthe piston during its return blow the air having entered into it in adirectional air jet on to the drawn article which might cause thearticle to jump back into the draw die from which it is meant to beejected.

The circuit arrangement is shown in FIGS. 9 and 10. The voltage derivedfrom the mains is applied at 8 1 to a switch which transmits the currentpulse through the relay 82 to the first time delay relay 83. Thepotentiometer 87 by which a time has been set allows, after this timehas expired, the contact spring 85 to be released, which on the onehand, breaks the con-tact 86 and, on the other hand, makes the contact34. The latter is made only for the fraction of a second, whereupon therelay, as shown, again drops back into its idle position. At the sametime, however, the time delay relay 88 has started to function. Here thesame process evolves as in the preceding time delay relay, in accordancewith the time set on the associated potentiometer, and the pulse is nowfurther transmitted to the time delay relay 89. Here, too, the describedprocess is repeated and this is continued up to the last relay whichthen energizes again the first relay 83.

A voltage is applied to the cross bars 91, 9t) and 92. By connectionsmade with the aid of special plugs this voltage may be selectivelytransmitted to the cross bars 93, in such a way that the voltage isapplied to the holding contacts of the relays 96, $7, 98 coupledthereto. The connection pulse momentarily transmitted by way of contact84 reaches the cross bar 99. If the latter is for example connected bythe plug 1% to the cross bar 101, the pulse passes to the relay 96 andattracts the relay coil whereby the contact bridge 102I03 is closed. Thecontact 103 may for example be held in this position through the plug104 as a holding contact in conjunction with the third time delay relayof the step-by-step switching mechanism. Only after the triggering andthe expiry of the delay time of the third relay is this contact bridgeinterrupted at the relay 89 so that in this way the contact bridge1021tl'3 is interrupted and the relay 96 d e-energized. At the sametime, for example, the magnetic valve 105 is also connected, inconjunction with the connection pulse of the time delay relay and theclosing of contact bridge 8483. The operating cylinder 106 moves in apre-determined direction. The process is again reversed by the timedelay relay 89 which, triggered by the time delay relay 88, momentarilyinterrupts the contact bridge leading to the cross bar 92. Thereby alsothe holding contact to 103 is interrupted and the relay 96 opened. Atthe same time the voltage supply at the magnetic valve 105 isinterrupted and the operating cylinder 1% returns into its normalposition. This perpetual cycle which is capable of accurate timing bymeans of the step-by-step switching mechanism and whose connectionpulses are conducted through the above-described cross bar distributorin a suitably selected sequence, by means of associate relays, tomagnetic valves and operating cylinders and other operating devices andin this arrangement can be cancelled also in a suitable manner by meansof the cross bar distributor 9t 95 can also be changed over, in anyphase, from its rhythm to hand switching. To do so the key 107 isdepressed which in the illustrated position supplies a voltage to theholding contact for relay 82 and interrupts energization of this relaywhen actuated. Thus the voltage supplied to the stepby-step mechanism isinterrupted and it ceases to function. At the same time the contactbridge 108109 is closed and a voltage supplied to 110' which then allowsfor example the magnetic valve 111 and thus the operating cylinder 112to be triggered by hand. When the contact bridge 163-409 is interrupted,permanent connection to relay S2 is reestablished. A switching pulsethrough switch 81 triggers the step-by-step switching mechanism and thetime delay relay 84 again starts, after the preset time has elapsed,with the above-described operation of the step-by-step switchingmechanism. It is also possible of course to arrange hand switching insuch a way that it closes the permanent contacts of the relays 96, 97,98 and that a further switch effects interruption.

For claritys sake, in the diagram the only switching by permanentcontact shown is through the contact bridge 1G8109, directly to themagnetic valve 111.

The operational cycle of the machine illustrated here evolves in thefollowing manner:

At first the machine is set to Zero which comes about automatically byletting the motor start up for a short period while the step-by-stepswitching mechanism is disconnected and the hand switch not touched.Then the heater bank 49 and, if desired, the motor 55 are connectedwhich are permanently supplied with current during operation of themachine. Both may also be connected and disconnected during operation ofthe machine, according to the repetitive cycle and the operating speed.Individual radiators may also be reguiated by means of electronic valvesand a circuit breaker element (birnetal interrupter) and pulsetransmissions. Then the beginning of foil web 34 is pulled off the roll33 to such an extent that a sufiiciently heated foil section is situatedin the plane of the draw operation and the leading end I of the web isfixed to the take-off spindle 40.

Now the machine is started by switching on the motor if this has notbeen done before, and an extraneous pulse is transmitted to thestep-by-step switching mechanism. When the time set on the potentiometerhas expired there is effected, on the one hand, an interruption of thesupply voltage for an associate cross bar at the first time delay relaywhich interruption de-energizcs the electric valves. But there is alsotriggered a connection pulse for another cross bar which connects thevalves. Besides the step-by-step switching mechanism ensures thattogether with this operation already the second time delay relay isactuated which, after expiry of the pre-set time, again transmits in oneand the same operation an appropriate pulse to another two bars of thecross bars distributor for on and off and to the third relay. Betweenthe cross bar distributor and the electric valve a relay is connected toallow time intervals between on and off switching to be bridged, sincethe step-by-step switching mechanism only transmits pulses. The first ofthese relays acts upon the associate electric valves 58. The lattermoves the hydraulic cylinder 12 in an upward direction whereby the elbowlever 11 is stretched to the left. The latter pulls to the left theframe carrying the die closing plate 7 and the end plate 16, almost upto the foil web 34 situated in the plane of the draw operation. By nowthe first time delay relay has run off and transmits the second pulsewhich passes through the cross bar distributor to the second relay andto the second time delay relay; by means of the electric valve 58allocated to the second relay the main cylinder 17 is actuated whichdisplaces the draw die 62 with its annular marking edge 63 to the rightin direction of the foil web until contact is made with the counter edge64 of the draw die 67. In this way notching of the foil web along theouter periphery of the blank to be drawn is effected. By now the secondtime delay relay has run off and transmits a pulse passing to the thirdrelay and the third time delay relay. The electric valve 58 allocated tothe third relay now brings about in the now closed draw die reduced orexcess pressure in the ducts 66 and 69 respectively, or actuates thedraw plunger 70. It is also feasible, by the additional connection of afurther relay and time delay relay, to generate reduced or excesspressure in a first operational phase and to actuate the plunger in asecond phase, or vice versa.

Notching and drawing is thus terminated and the third time delay relayhas run off. A fresh pulse is transmitted which is conducted to thefourth relay and the fourth time delay relay. The electric valve 58allocated to the fourth relay releases the clamping pressure between theguide frame 29 and the pressure frame 31 so that the margin of the foilweb is released. By then the fourth time delay relay has run off andtransmits the next following pulse which is conducted to the fifth relayand the fifth time delay relay. By means of the electric valve 53allocated to the fifth relay the feed cylinder 26 is actuated whichdisplaces the feed frame 18, 19, 2t 21 upwardly during which movementthe pressure frame 31, 32 remains in the open position, i.e. out ofcontact with the guide frame 29, 30.

The fifth time delay relay has now run off and transmits the next pulseto the sixth relay and the sixth time delay relay. The sixth relayactuates through its electric valve the pressure cylinders 27, 28 whichurge the pressure frame 31, 32 against the guide frame 29, 30 and clampthe foil web therebetween. The operation of pressing and clamping thefoil section, and of releasing it, and of its subsequent displacement bythe feed mechanism can also be combined to form one distance-dependentfunction so that only one magnetic valve will be sufficient for itscontrol since this operation is always repeated in the same way.

Pressure in the main cylinder 17 is still maintained at this stage.Running off of the sixth time delay relay however, by a pulsetransmitted to the seventh relay and the relevant electric valve,actuates the hydraulic cylinder 12 in the opposite direction so that theelbow lever 11 is returned and lets the still loaded marking ring 62penetrate the die 67 further, the die covering plate 68 acting as alimit so that the chilled marking area at the margin of the blank isruptured and breaks away from the foil web. After the draw tool 62 haspassed through the die 67 the draw plate 14 supporting the tool 62 isreversed while an ejector '76 arranged in the tool 62 still follows inthe direct-ion of the die closure plate 63. In this way the drawnproducts are removed from the tool and, after being urged out of thestatic field of the ejector by the separator 77, fall by way of a chuteor the like into a storage container (likewise not shown).

As soon as the tool 62 and die closure plate 68 are separated by themaximum possible distance, and ejector and plunger have been returned totheir original positions, also the seventh time delay relay has run offand supplies a new pulse for the eighth relay and the eighth time delayrelay. The eighth relay now actuates the feed cylinder 26 in oppositedirection, by means of its associate electric valve, so that thiscylinder returns the feed frame 18-32 together with the film web heldbetween the pressure frame 31, 32 and the guide frame 29, 30 in adownward direction into the position shown in FIG. 1, while the pressurecylinders 27, 28 hold the pressure frame 31, 32 in the advanced clampingposition.

Thus also the eighth time delay relay has run off and supplies a pulsewhich is conducted to the first relay and the first time delay relay,whereby the next-following operational cycle is set in motion.

The above-described embodiment relates to a timedependent control bymeans of time delay relays which has proved very satisfactory inpractical operation. But it is also possible to make the controldependent on distance by providing end position switches instead of timedelay relays which are actuated as soon as the member to which they areallocated has covered the distance prescribed for it. If necessary, itis possible also to combine within the machine time dependent anddistance dependent control.

In a single-purpose machine, previously tested in regard to its toolperformance by the above-described :multi-purpose machine, the cross bardistributor can be omrnitted and the step-by-step switching mechanism sodevised that it. supplies the pulses directly to the valves.

. 17 But this is based on the assumption that the tool and its functionhave been irrevocably fixed and are not expected to be modified duringthe life of the machine.

As mentioned before, the punching and drawing operations may also beseparated in time so that when the draw die is opened and the foiladvanced, the blanks are still suspended in a marked condition in thefoil web. Provided that the machine is further developed to this end, asubsequent station in the path of foil advancement can then be providedfor carrying out the punching operation by which the blanks areseparated from the foil web. Generally this will not offer anyadvantages. But this lay-out may be advisable if the draw tool mustexecute very complicated draw operations and it appears desirable,therefore, to devise it as a pure draw tool without any other functions.In this case pure punching tools, without additional functions, are thenprovided in a subsequent station along the feed track. An essentialrequirement in such a case will be a completely uniform and accuratefunctioning of the feed mechanism.

The present processis suitable for deep drawing plates and foils of allkinds of thermoplastic material which lend themselves to deep drawing.Apart from polyvinyl chloride and its co-polymers, with or without theaddition of a plasticizer, it is equally possible, according to themethod of the invention, to use for example polyvinylidene chloride,polyacrylic acid esters, polymethacrylic acid esters, polyacrylonitrile,polystyrene, polyethylene and polymeric higher olefines,polyisobutylene, poly-fiuorolefines and polychlorofiuorolefines as wellas the co-polymers of the monomers corresponding to the above-mentionedpolymeric products, and mixtures with one another of the quotedpolymers.

Patent claims:

1. A method of continuously producing deep drawn articles from a foilweb of thermoplastic material comprising the steps of discontinuouslyfeeding a foil web, making said foil web drawable by heating it,pre-grooving said foil to mechanically form a border along theperipheral outline of the drawn article to be produced, performing saiddrawing operation, allowing said foil to cool to embrittle itspre-grooved border, and subsequently ejecting said drawn article fromthe foil web by breaking said embrittled pre-grooved border.

2. A method of continuously producing deep drawn articles from asynthetic foil in a die comprising the steps of discontinuously feedinga foil web through said die, making the portion of said web in said diedrawable by heating it, mechanically pro-grooving said foil along theoutline within which the deep drawn article is to be drawn, effectingdrawing at the same temperature as pre-grooving, chilling the markedperipheral zone of the blank to the point of brittleness, and finallyejecting the drawn article from the die and simultaneously breaking itaway from the foil web at said pre-grooved outline.

3. A method as set forth in claim 2 wherein the foil web advance and theintensity of its heating is controlled in dependence upon its plasticityprior to entering the zone of treatment.

4. A method as set forth in claim 2 wherein said mechanical pre-groovingis accomplished by pressing the foil upon a support disposed within anaperture in a die, and subsequently driving the foil and support intothe die to rupture the connection between the foil and the portiondisposed upon said support.

5. A method of continuously producing deep drawn articles from a foilweb of thermoplastic material comprising the steps of heating said foilweb to an easily deformable condition, pressing said heated foil web ashort distance through an aperture onto a support to score a groovedborder around the portion of said web to be drawn into said article,forcing the portion of said foil web within said border into a cavity insaid support to draw said article, allowing said foil web to cool toembrittle said grooved border, andthen driving said drawn portion ofsaid foil web together with said support completely through saidaperture to sever said drawn article from the remainderof said web. I

6. An apparatus for producing deep drawn articles from a plasticmaterial comprising an apertured plate, a reciprocating plunger arrangedto pass a predetermined distance through the aperture in said plate, asharp-edged ring disposed upon the side of said aperture plate fromwhich said plunger emerges, reciprocating means alternately driving saidsharp-edged ring towards and away from said apertured plate forreceiving and urging a heated plastic blank against said apertured plateand notching a border upon it, said predetermined movement of saidplunger being sufiicient to first draw said article from said plasticblank held between said apertured plate and said ring and then sever itfrom said blank, and said plunger and ring being arranged tocumulatively absorb enough heat from said drawn article to embrittlesaid notched border before said plunger moves to its extremity of travelthereby facilitating the severance of said article from said plate.

7. An apparatus for continuously producing deep drawn articles from afoil web of thermoplastic material comprising an apertured plate, aplunger mounted to move through the aperture in said plate, a markingdeviceincorporating a ring-shaped member having a sharp edge spacedslightly outside of the outline of said aperture disposed upon theopposite side of said plate from said plunger, a means for feeding saidfoil between said ringshaped member and said plate, heating means forsoftening said foil, and reciprocating drive means for first moving thesharp edge of said ring-shaped member into contact with said softenedfoil for marking it and for subsequently driving said plunger throughsaid foil to deep draw it and then sever the deep drawn article fromsaid foil at said marked edge when it has become brittle upon cooling.

8. An apparatus as set forth in claim 7 wherein an auxiliary plate isdisposed beyond said ring-shaped member for cooperating with saidplunger in forming the bottom of said deep drawn article and forconducting heat away from it to help embrittle said marked portion.

9. Anapparatus as set forth in claim 7 wherein said marking device isarranged within said apertured plate.

10. An apparatus as set forth in claim 7 wherein a cooling device whichblows air upon said foil is provided, a feeler for determining thedegree of softening of the foil web in the heating area is provided, andsaid feeler being connected to actuate said cooling device forprotecting said foil Web from burning.

11. An apparatus as set forth in claim 10 wherein said feeler for thefoil web is connected by means of a parallelogram linkage to a brakingdevice which influences the foil web advance.

12. An apparatus as set forth in claim 7 wherein a fine-feed regulatingmechanism and a shock absorber are connected to the means for feedingsaid foil to prevent it from breaking.

13. An apparatus as set forth in claim 7 wherein the heating system forthe foil web is constituted by a bank of infra-red radiators, and theradiation area of such bank corresponds to the height of the foil web tobe heated in any particular case.

14. An apparatus as set forth in claim 7 wherein a foil brake isarranged at the supply spindle and the take-off spindle for the foilweb, said brake being connected to a lever pivotable about its own endpoint, and said lower carrying at its free end a conveying roller whichfits into the first deflected loop of the foil web.

15. An apparatus as set forth in claim 7 wherein a permanent brake forthe foil web is arranged at the point of deflection above the heatingarea, and said brake being constituted by a beam lined with resilientmaterial which bears on the web.

16. An apparatus as set forth in claim ,7 wherein drawing cylinders areallocated to the die plates carrying a draw plate anda die closureplate, said drawing cylinders including a pressure ,side exposed to airpressure and a rear side exposed to oil pressure, the fully stressedpiston surface representing the pressure side of the draw cylinder beingstressed by a constant air pressure so that the oil present in the rearcompartment of the cylinder is driven by the draw end of the cylinderwhich continuously pulsates in both directions with the piston movement,and said drawing cylinders being arranged diagonally on a stationarymachine frame.

17. An apparatus as set forth in claim 7 wherein a discontinuousfoil-feeding mechanism is provided, said mechanism including a doubleclamping device comprising a stationary and a movable clamping device,said clamping devices being mutually adjustable in their operationalcycles so that at any time one of them engages the foil web and clampsit, the movable clamping device being arranged for again returning toits uppermost position immediately after having reached the extremepoint of its downward movement eflFecting the foil advance, the path ofthe movable clamping device being situated within that portion of theguide track which is irradiated by the heating system, and the clampingdevice being automatically controlled independently of the switchingcycle of the machine.

18. An apparatus for continuously producing deep drawn articles from afoil web of thermoplastic material comprising an apertured plate, areciprocating plunger which passes through said aperture, a ring-shapedknife having an outline slightly larger than said aperture, said knifebeing disposed adjacent the aperture in said plate, and being disposedupon the side of said plate upon which said plunger passes out of saidaperture with said knife encompassing said aperture, means for feeding acontinuous foil web between said ring-shaped element and said aperturedplate, the edge of said knife being sharpened for grooving said foil webby contact therewith when said foil web is made drawable by heating it,a heater for making said foil drawable when it is positioned betweensaid apertured plate and said ring-shaped member, reciprocating meansreacting between said apertured plate and said ring-shaped knife forforcing said sharpened edge of said knife into said foil web when it isbacked up by said apertured plate to score a grooved outline upon it,coordinating means for driving said plunger through said heated foil webheld between said apertured plate and said ring-shaped member fordrawing said articles, said coordinating means subsequently holding saidplunger and drawn article in contact with each other a sufficient timeto absorb enough heat from it to embrittle the grooved portion of saidweb, and severing means for subsequently breaking said article from saidweb at said embrittled border by further movement of said plungerrelative to said web.

19. An apparatus as set forth in claim 18 wherein an auxiliary plate ispositioned a predetermined distance away from said aperture in front ofthe path of movement of said plunger, and the opposed surfaces of saidplunger and said auxiliary plate being cooperatively formed to shape thebottom of said article between them.

References Cited in the file of this patent UNITED STATES PATENTS2,282,423 Kopitke May 12, 1942 2,547,331 Lent Apr. 3, 1951 ,891,280Politis -a June 23, 1959

